Degrees
A degree is a unit of measurement used to measure angles.
We can measure all Angles in Degrees.
There are 360 degrees in one Full Rotation (one
complete circle around
The Degree Symbol: °
We use a little circle ° following the number to mean degrees.
For example 90° means 90 degrees
Angles
In One DiagramThis diagram might make it easier to remember: Also: Acute, Obtuse and Reflex are in alphabetical order. 
Supplementary Angles
These two angles (140° and 40°) are Supplementary Angles, because they add up to 180°.
Notice that together they make astraight angle. 

But the angles don’t have to be together.
These two are supplementary because 60° + 120° = 180° 
Complementary Angles
Two angles are Complementary when they
add up to 90 degrees (a Right Angle ).
These two angles (40° and 50°) are Complementary Angles, because they add up to 90°.Notice that together they make a right angle . 

But the angles don’t have to be together.
These two are complementary because 27° + 63° = 90° 
Angle Relationships
Interior Angle
An Interior Angle is an angle inside a shape.
Exterior Angle
The Exterior Angle is the angle between any side of a shape, and a line extended from the next side.
Angles On One Side of A Straight Line
Angles on one side of a straight line will always add to 180 degrees.
If a line is split into 2 and you know one angle you can always find the other one.
30° + 150° = 180°
Interior Angles of Polygons
An Interior Angle is an angle inside a shape.
Triangles
The Interior Angles of a Triangle add up to 180°
90° + 60° + 30° = 180° 
80° + 70° + 30° = 180° 
It works for this triangle! 
Let’s tilt a line by 10° … It still works, because one angle went up by 10°, but the other went down by 10° 
Quadrilaterals (Squares, etc)
(A Quadrilateral has 4 straight sides)
90° + 90° + 90° + 90° = 360° 
80° + 100° + 90° + 90° = 360° 
A Square adds up to 360° 
Let’s tilt a line by 10° … still adds up to 360°! 
The Interior Angles of a Quadrilateral add up to 360° 
Because there are Two Triangles in a Square
The interior angles in this triangle add up to 180°
(90°+45°+45°=180°) 
… and for this square they add up to 360°
… because the square can be made from two triangles! 